1. Field of the Invention
The present invention relates to a new diagnosis method of endometriosis by detecting biochemical marker in serum, in particular alpha 1-antitrypsin, fragments of alpha 1-antitrypsin, or a combination of both.
2. Description of the prior art
Endometriosis has been a disease which is most frequently found in women at reproductive age [Guarnaccia et al. 1997]. Many pre-menopausal women suffer from endometriosis over a long period of time. The most common symptom is menstrual pain whereas in serious cases endometriosis may cause woman's infertility [Giudice et al., 2004]. Researchers have been making efforts in realizing the aetiology of endometriosis. Although its treatment have become easier, the mechanism leading to endometriosis is not clear so far. With respect to women without any disease symptoms the prevailing rate of endometriosis is 2%-22%. With respect to women with disease symptoms (e.g. menstrual difficulties, menstrual pain) the prevailing rate of endometriosis is.40%-60% [Farquhar, 2000; Kyama et al., 2003]. Among the women who suffer from menstrual pain during their menstrual period there are 13%-33% that suffer from infertility [D'Hooghe, et al., 2003]. Endometriosis is a disease characterized by the presence of endometrial tissue at ectopic sites, i.e. glands and stroma cells of endometrium which should grow inside the uterus grow at sites outside the uterus, preserving the same physiological form of a normal endometrium. Human uterine wall consists of three layers: endometrium, myometrium, and porous layer (from inside toward outside). Endometrial cells at ectopic sites also exhibit periodic changes due to influence of hormones, e.g. proliferation, degradation, bleeding, etc. If the nidus occurs at myometrium, it is called as adenomyosis. If the nidus occurs in the ovary, it is called chocolate cyst. If the nidus occurs at the pelvic cavity, it is called as pelvic endometriosis [Sampson et al., 1921].
In the diagnosis endometriosis is usually discovered based on the pain during patient's menstrual period and physiological inspections of abdominal cavity. Serious pain may be accompanied by pain of the rectum, even resulting in fever. However, if only symptoms are considered, the discovery may be delayed, leading to more serious condition. Therefore, the diagnosis of endometriosis has to be based on a combination of a variety of many observations and scientific inspection methods, including filtering symptoms, analyzing disease history, inferring according to clinical information. With help of palpation and methods such as ultrasonic diagnosis conjecture can be made about condition of the abdominal cavity and the pelvic cavity. Nevertheless, the gold standard of the diagnosis still depends on laparoscopy, in order to confirm the occurrence of endometriosis.
Although laparoscopy provides the gold standard of endometriosis, its acceptance is quite low because of the need of invasive procedure. Furthermore, laparoscopy in which endometriosis is to be observed optically has drawbacks such as difficulties in discovering the nidus at some sites, e.g. back sites of the pelvic cavity, sites surrounding intestines and stomach. On the other hand, vaginal ultrasonic method and nuclear resonance imaging (MRI) are taken to observe endometriosis occurring at the abdominal cavity and the ovary. These two techniques are more sensitive with respect to fibroid or chocolatecyst of more than 2 centimeter, but their sensitivity with respect to endometriosis is still very low. Barbieri in 1986 first proposed that CA125 in serum of a patient with endometriosis increases [Barbieri, 1986]. It is to be noted that an increase of CA125 usually relates to several physiological and pathological conditions, e.g. arrival of menstrual period, pregnancy, inflammation of the abdominal cavity, intimal arteritis, breast cancer, liver cancer, lung cancer, etc. The sensitivity is only about 15% to endometriosis. Because especially in the early stage of endometriosis CA125 shows almost no increase, the practical use of CA125 as a marker is limited. Only for cases in which CA125 has increased before the operation, it can be taken as a trail for reference. It is still to be noted that ovary tumor is found in patients of endometriosis as well as ovary cancer. CA125 increases in both cases that can not be differentiated in spite of performing specific Doppler-ultrasonic inspection on the blood stream. In general, CA125 in patients of endometriosis is usually about 100 U/ml and hundreds or even thousands times higher in patients of ovary cancer. During the operation of a patient of chocolate cyst whose CA125 is above 500 U/ml, laparascopical inspections should be performed carefully. Very careful inspection and cytological analysis of ascites can not be left out to find suspicious nidus indicating ovary cancer and endometriosis that should be further pathologically analyzed [Acien et al., 1989; Kennedy et al., 1990]. In fact, in the diagnosis application of CA125, the level of CA125 in a patient's serum is measured monthly when menstrual sign begins. This helps to diagnose depth endometriosis. When the baseline level of CA125 in serum is set to be 25 U/ml, the sensitivity and specificity with respect to endometriosis are respectively 67% and 90%. Therefore, CA125 is now taken by some doctors as a help of diagnosing endometriosis. For the moment, ultrasonic and blood inspection can be taken as a reference for diagnosis. The ultimate determination still depends on high invasive inspection methods such as laparoscopy. Be assisted with the image taken by an endoscope, a clinical doctor can inspect in detail within the abdominal cavity, the uterus, the oviduct, the ovary, and intrusion of uterus sacrum's ligament. During the inspection the doctor can use electric burning or perform excision to remedy. But there are many empirical differences in laparoscopic observations. For endometriosis there can be small nidus or large cyst which may be dark brown, black, or even white or yellow due to thick walls. When in serious situation of endometriosis a cyst is broken and chocolate-like liquid flows out, adhesive and grey scare tissues, black granular, even bubble-formed or tear-formed cyst as flame-like nidus can be seen everywhere in the abdominal cavity. Only a very experienced doctor can make a correct diagnosis and performs the remedy at the same time.
Proteomic approaches are now adopted by scientists to detect occurrence of diseases or biochemical markers for cancer. Proteomics as a research field on biochemical markers has developed better and better. As related to dealing with specimen, analysis with uni- or two-dimensional gel electrophoresis, analysis of images, and mass spectrometry analysis there have been lots of reported researches[Anderson, 2002; Adkin et al., 2002; Chan et al., 2004 Chen et al., 2005, Zhou et al., 2004; Zhou et al., 2005].
In human serum alpha 1-antitrypsin is one of the proteins contained significantly in the serum. Its molecular weight is about 52 kDa. Alpha 1-antitrypsin is called as protease inhibitor (Pi) due to its action mechanism, belonging to the supergene family. Its main function is to reduce neutrophil elastase that is secreted by leukocytes in the immune system. Neutrophil elastase is a protease which assists human immune system in protecting from bacteria and foreign harmful materials. As to the structure alpha 1-antitrypsin exhibits three isoforms of differences in glycosylation, as characterized by three different structures formed with different amounts of oligosaccharide group and sialic acid [Carrell, 1982].